Effect of feeding regimens on polyhydroxybutyrate production from food wastes by Cupriavidus necator

We investigated the effects of different feeding regimens (1-pulse, stepwise, and continuous) of fermented food-waste liquid on polyhydroxybutyrate (PHB) production. The fermentation liquid was filtered with a membrane filter (pore size, 0.45 μm) to remove anaerobic microorganisms and solids and used as a carbon source for Cupriavidus necator. One-pulse feeding yielded the highest cell concentration of C. necator. However, the PHB concentration was higher in the stepwise- and continuous-feeding regimens. Therefore, the continuous-feeding regimen was used for continuous PHB production. PHB could be produced over 259 h (8 draw-fill cycles) with a maximal PHB content of 87%, but the PHB concentration and content decreased with an increase in the operation time.